Ignition system for internal combustion engines



M/of/ws/s p 1938- L. H. SCOTT 2,131,018

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed July 22, 1936 F W 'WI I ll,

A ORNEY.

UNITED STATES PATENT OFFICE IGNITION SYSTEM FOR INTERNAL COM- BUSTION ENGINES Lloyd H. Scott, Sidney, N. Y., assignor to Bendix Aviation Corporation, South Bend, 11141., a corporation of Delaware Application July 22, 1936, Serial No. 91,927

7 Claims. (01. 123-148) The present invention relates to an ignition shunted around the breaker mechanism, and a system for internal combustion engines and more ground switch 6 being also provided to render particularly to a dual spark ignition system in the device inoperative when closed. The primary which two spark plugs in each cylinder are opercircuit is completed through the ground as indi- 1 A ated concurrently from a single source of high cated in the usual manner. The secondary of 5 tension current. the coil is connected by a lead I to the spark Dual spark systems heretofore proposed have plugs 8 and 9 arranged in parallel, the secondary in general been subject to the limitations that circuit being completed through the ground as if a single source of high tension current were usual.

in employed, the arrangement was either that the According to the present invention, a pair of 10 in which:

voltage of such source was divided between the condensers l l and I2 are introduced in series two spark gaps, thus necessitating a voltage with the spark plugs 8 and 9, the capacity of said source correspondingly higher than usual, or else, condensers being large enough to store up a if a parallel arrangement were used, the current major fraction of the energy of a discharge from tended to flow'through the gap of least resistthe secondary 2 of the ignition coil and each of 15 ance, and if one plug fouled, the other plug could said condensers being large enough so that the not operate. ratio of its capacity to the inherent capacity of It is an object of the present invention to proits series spark plug is large in order that subvide a dual spark ignition system for internal stantially full voltage of the secondary be applied combustion engines which is efiicient and reliable across each spark plug, but being small enough so 20 in operation and simple and economical in conthat. such secondary discharge will charge the struction. condensers to a voltage substantially above the Another object is to provide such a device in break-down voltage of the spark plugs. which the full voltage of the source of high ten- The condensers l i and i2 are preferably though sion current is applied to each spark plug. not necessarily formed as a unit as illustrated 25 It is another object to provide such a device in in Figs. 2, 3 and 4. As best shown in Fig. 4, which the total energy of the source of high tenalternate sheets or plates l3 of conductive matesioncurrent is divided between the spark plugs. rial such as tin foil are interspersed between It is a further object to provide such a device similar sheets l4, being separated therefrom by no in which fouling or shorting of one spark plug sheets l5 of dielectric material such as mica.

tends to increase the energy of the discharge A second series of conductive plates 16 are simithrough the other plug. larly arranged in cooperative relation with an It is another object to provide such a device additional pack of plates M, the two packs of which incorporates means for increasing the inplates being separated by heavy sheets of ditensity and rapidity of discharge through the electric material l1. Sheets l3, l4 and I6 are 35 spark plugs. provided with laterally extending tabs l8, l9 and Further objects and advantages will be appar- 2| respectively, and the sets of tabs l8, l9 and ent from the following description taken in con- 2| are connected to the binding posts 22, 23 and nection. with the accompanying drawing in 24 respectively, the whole being preferably molded in a plastic dielectric material 25 to form an Fig. 1 is a wiring diagram of an ignition system integral unit.

embodying the present invention; In use, the binding post 23 of the double con- Fig. 2 is a plan view of a double condenser denser to which all the plates H are connected,

structure particularly adapted for use in the presreceives the lead I from the secondary 2 of the ent invention; induction coil, and the binding posts 22 and 2| 45- Fig. 3 is a side elevation thereof; and connected to the plates l3 and I6 are fixed to, Fig. 4 is an exploded view thereof showing the or connected with the spark plugs 8 and 9. arrangement of the condenser plates and inter- In the operation of an ignition system embodyposed sheets of dielectric material. ing the present invention, assuming the spark 5 Referring first to Fig. 1 of the drawing, there plugs 8 and 9 are in proper operative condition, a

is illustrated conventionally the primary winding discharge from the secondary of the coil, proand secondary winding 2 of an induction coll duced in the usual way by the opening of the of any suitable type of magneto. The primary primary circuit by the breaker 4, causes the conl is connected by a lead 3 to any suitable form denser plates l4 connected to the lead I to become of breaker mechanism 4, a. condenser 5 being charged. This charge induces a chargeoi op- 55 posite polarity on the cooperative condenser plates I3 and I6 whereby. a potential is built up across the gaps of the spark plugs 8 and 9 until the gaps break down and current flows through the gaps charging up the condensers. When the secondary discharge is dissipated and the voltage in the secondary lead falls, the condensers H, I! discharge back through the spark plugs 8 and 9, thus producing a second spark therein. The operation so tar described is in general the same as in case of a single ignition system having a series condenser in the secondary circuit, but it is to be noted that substantially the full voltage of the induction coil is applied equally to each spark plug, while the energy of the discharge is divided equally between the plugs. If, however, the spark plug 8, for instance, should become fouled and shorted, the condenser II is in effect shunted around the condenser l2. The condenser ll under these circumstances stores up a portion of the energy of the secondary discharge during the time that the secondary voltage is building up to the break-down voltage of the spark gap 9. When said gap breaks down, the condenser ii discharges through the gap, supplementing the energy coming from the lead I and causing an intensification of the spark across the gap 9.

It is further to be understood that although the invention has been here disclosed as applied to a magneto ignition system, it is also applicable to a battery ignition and distributor system with similar beneficial effects.

It will be readily seen from the above that with the disclosed arrangement, a proper division of the secondary energy between the plugs 8 and 9 is always secured when the plugs are in proper condition, and if one plug should become inoperative, the discharge across the other plug is reeniorced instead of being weakened.

Although but one form of the invention has been shown. and described in detail, it will be understood that other forms are possible and various changes may be made in the details and arrangements of the parts without departing from the spirit of the invention as defined in. the claims appended hereto.

What is claimed is: f

1. In a dual ignition system for internal combustion engines, a single source of high tension current, a pair of spark plugs, and means for applying substantially the full voltage of said source to each of said plugs while dividing the energy from said source between said plugs.

3. In a dual ignition system for internal combustion engines, a single source of high tension current, a pair of spark plugs, and means for applying substantially the full voltage of said source to each 01' said plugs, including means for dividing the energy from said source between the two plugs, said last means being so arranged that shorting one plug causes energy which would have produced the spark therein to reentorce the spark delivered at the other plug.

i. In a dual ignition system for internal combustion engines, a source of high tension current, a pair of spark plugs, a common cable for said plugs from said source, and means including an electrostatic condenser connecting each of said plugs to the common high tension cable.

5. In a dual ignition system for internal combustion engines, a source of high tension current, a pair oi! spark plugs, a common cable for said plugs from said source, and means including twin electrostatic condensers connecting said plugs in parallel with each other to said common cable.

6'. A dual ignition system for internal combustion engines including a source of alternating high tension current a pair of spark plugs, and a connection between said source and said plugs including a common cable and branches therefrom leading to the plugs, said branches including electrostatic condensers so arranged that if one plug should foul, the condenser in that branch will prevent grounding of the hightension cable and function as an intensifier for the other spark pl g.

7. A dual ignition system for internal combustion engines including a source of alternating high tension current, a pair of spark plugs, and a connection between said source and said plugs in eluding a common cable and branches therefrom leading to the plugs, said branches including electrostatic condensers so arranged that if one plug should foul, the condenser in that branch becomes in effect shunted around the other branch and operates to increase the energy and shorten the time period of discharge through the other plug. LLOYD H. SCOTT. 

